Master Chang, Wu Na(or Zhang, Wu Na) is pretty good. I trained with him for a while in Wudang Baguazhang. His system is basically a blend of the bagua passed down from Wudang masters Ma, Jie and Qian Timing, along with the training in Beijing Baguazhang with several masters, particularly Gao Jiwu. As far as the lineage on his website, I asked him about that. It wasn't written by him and is incorect. He doesn't teach Li Cunyi Baguazhang, but instead teaches Wudang Baguazhang. Last time I heard, he was working on changing the info on his website. It hasn't been done yet though.
I know he's had some contact with Zhang, Jie, but their bagua is totally different. Zhang, Jie's bagua is spent walking EXTREMELY slowly the entire time of one's training and very little explanation is put into fighting techniques. Also, if you want to learn anything, you have to take the private lessons with him which cost $100 per hour. Each lesson you can only learn one movement and the rest is spent on review. Sometimes, he even cuts the time short if he has other things going on.
Master Chang makes students walk slow in the beginning, but after a while they learn to move fast. Also every class ends with fighting techniques. Master Chang is very good in fighting. He knows Zhang, Jie and at one point Master Chang's gong fu sister Lu, Mei-hui was going to help Zhang, Jie with his book, but that ended up not happening. They have some forms in common that Master Chang has trained with Zhang, Jie, but he learned them elsewhere as well when he was training in Beijing. Besides, the two masters do them differently.
I suggest checking out Master Chang's school for some good bagua, but don't pay too much attention to his website for now;)
- Mr. Blond